This 20mm pancake lens from Panasonic for Micro Four Thirds system cameras costs around £290 and sports a bright maximum aperture of f/1.7 and internal focusing.

Those looking for a standard lens with a fast maximum aperture may also consider Panasonic’s 25mm f/1.4 Leica D Summilux optic. This lens costs a lot more at around £550 and isn't as compact as this 20mm lens, but sports a faster maximum aperture of f/1.4.

Panasonic 20mm f/1.7 Lumix G Handling and features

Being a pancake lens, this optic is very compact, and will make a pocketable combination with many Micro Four Thirds system compatible camera bodies. It weighs only 100grams, and compliments the Panasonic Lumix G3 used for testing very well.

The lens barrel is constructed from high quality plastics with a gun metal finish, and much of this space is filed with the rubberised focus ring, which has just the right amount of resistance for making fine manual focus adjustment easily.

As focusing is performed internally, the 46mm filter thread does not rotate and the lens does not extend, making it perfect for use with graduated and polarising filters. Autofocus speeds are good and focus is virtually silent.

Panasonic 20mm f/1.7 Lumix G Performance

At maximum aperture, sharpness in the centre of the frame is already excellent and the clarity produced towards the edges of the frame is very good. Stopping the lens down to f/4 improves the sharpness towards the edges to excellent levels and outstanding levels in the centre. Smaller apertures result in a loss of sharpness due to diffraction, but the quality is still very good across the frame down to f/11.

Resolution at 20mm

How to read our charts

The blue column represents readings from the centre of the picture frame at the various apertures and the green is from the edges. Averaging them out gives the red weighted column.

The scale on the left side is an indication of actual image resolution. The taller the column, the better the lens performance. Simple.

Chromatic aberrations are reasonably well controlled, increasing in strength towards the edges of the frame as the lens is stopped down. Even at their worst at f/16 CA levels are low enough to cause few issues, even in large prints, or harsh crops from the edges of the frame.

Chromatic aberation at 20mm

How to read our charts

Chromatic aberration is the lens' inability to focus on the sensor or film all colours of visible light at the same point. Severe chromatic aberration gives a noticeable fringing or a halo effect around sharp edges within the picture. It can be cured in software.

Apochromatic lenses have special lens elements (aspheric, extra-low dispersion etc) to minimize the problem, hence they usually cost more.

As falloff and distortion are corrected by the camera's image processing engine when shooting JPEGs, falloff and distortion will only be easily visible when shooting in RAW format.

For a wide aperture lens, falloff of illumination towards the corners of the frame is reasonably well controlled. At maximum aperture the corners are 1.71 stops darker than the image centre and visually uniform illumination is achieved at f/2.8.

A slight amount of barrel distortion is present in images taken with this lens, but the low level of 0.405% detected by Imatest should pose few issues in practice. If absolutely straight lines are critical, this low level of distortion should be relatively easy to correct as the distortion pattern is uniform across the frame.

This lens is reasonably resistant to flare, even with very bright light sources in the frame. Contrast levels do tend to drop off fairly dramatically when shooting into the light though, so care may need to be taken under those conditions.

Panasonic Lumix G 20mm F/1.7 Pancake Lens Sample Photos

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Panasonic 20mm f/1.7 Lumix G Verdict

Those looking for standard lens with a fast maximum aperture cant go far wrong with this lens. It delivers sharp, contrasty images, focuses fast and is compact enough to make a pocketable combination with your Micro Four Thirds camera.

The price of £290 isn't bad either, with all things considered, such as the sharpness delivered and build quality. This lens represents even better value if picked up as part of a kit with a camera.